I generally wear cycling bibs and tights with no chamois in weather down to about 20 F. Lower than that I wear a pair of heavily insulated full legged bibs with wind stopper material over regular bibs.
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A conclusion is the place where you got tired of thinking. - S. Wright
Favorite rides in the stable: Indy Fab CJ Ti - Colnago MXL - S-Works Roubaix - Habanero Team Issue - Jamis Eclipse carbon/831